The terrorist attacks of Sep. 11, 2001 in New York City and Washington, D.C., and the current war in Iraq, have heightened the need for ballistic armor. Military vehicles, in particular, are vulnerable to higher-potency weapons such as rocket-launched grenades and other projectiles. Military personnel want lightweight, fast and maneuverable vehicles, but they also want vehicle occupants to be fully protected. Ballistic steel armor plates, while relatively inexpensive, add thousands of pounds to a vehicle, many of which were not designed to carry such loads. This has resulted in numerous engine and transmission failures as well as problems with vehicle suspensions and brakes. The additional weight reduces fuel efficiency and makes it impossible to carry additional personnel in the vehicle in case of emergency. For these reasons, designers are beginning to adopt more lightweight composite armor across the board for military and tactical vehicles.
Various lightweight armor designs are now becoming commercially available. Cellular Materials International, Inc. of Charlottesville, Va. offers a product called Microtrussm, a periodic cellular material designed to absorb a larger amount of energy than solid material of equal mass. When a blast hits the face of the sandwich panel, the face plate will stretch and wrinkle followed by the propagation of the impulse force into the core. The core will then buckle and collapse, absorbing the maximum kinetic energy of the blast. The back face plate takes the remaining blast pressure towards the end of the blast event where the intensity of the impulse force is considerably reduced. Thus, the periodic structure maximizes the absorption of the impulse energy created by the blast and distributes or diffuses the intensity of the force, leading to protection of the assets behind the sandwich structures.
Designs using ceramic pellets are also evolving. U.S. Pat. No. 6,203,908 is directed to a composite armor for absorbing and dissipating kinetic energy from high velocity projectiles. The armor comprises a panel having a layer of a plurality of high density ceramic bodies, the bodies having a specific gravity of at least 2 and being made of a material selected from the group consisting of ceramic material which does not contain aluminum oxide and ceramic material having an aluminum oxide content of not more than 80%. Each of the bodies is substantially cylindrical in shape, with at least one convexly curved end face, and each of the bodies having a major axis substantially perpendicular to the axis of its respective curved end face, wherein the ratio D/R between the diameter D of each of the cylindrical bodies and the radius R of curvature of the respectively convexly curved end face of each of the bodies is at least 0.64:1, and wherein the bodies are arranged in a plurality of adjacent rows and columns, the major axis of the bodies being in substantially parallel orientation with each other and substantially perpendicular to an adjacent surface of the panel.
Ballistic armor utilizing ceramic components is also commercially available. ARES Protection, Le Bourg 38270, Primarette, France offers a product called LIBA, which stands for light improved ballistic armor. The armor is a system consisting of one or more layer(s) of spherical ceramic pellets glued with (or without) a backing material and embedded in a polyurethane matrix LIBA is for body and vehicle protection applications, especially to stop AP ammunitions. LIBA is developed for protection against WC bullets and hollow charges.
Despite these advances, the need remains for an improved, more optimized lightweight composite armor for military and tactical vehicles and other applications.